Lenses capable of post-fabrication power modification

ABSTRACT

The present invention relates to lenses that are capable of post-fabrication power modifications. In general, the inventive lenses comprise (i) a first polymer matrix and (ii) a refraction modulating composition that is capable of stimulus-induced polymerization dispersed therein. When at least a portion of the lens is exposed to an appropriate stimulus, the refraction modulating composition forms a second polymer matrix. The amount and location of the second polymer matrix may modify a lens characteristic such as lens power by changing its refractive index and/or by altering its shape. The inventive lenses have a number of applications in the electronics and medical fields as data storage means and as medical lenses, particularly intraocular lenses, respectively.

This application claims the benefit of (i) U.S. Provisional ApplicationNo. 60/115,617 filed Jan. 12, 1999 filed by inventors Jagdish M.Jethinalani, Daniel M. Schwartz, Julie A. Komfield, and Robert H. Grubbsentitled SILICONE IOLS EMBEDDED WITH PHOTOSENSITIVE COMPOSITIONS; (ii)U.S. Provisional Application No. 60/132,871 filed May 5, 1999 filed byinventors Jagdish M. Jethmalani, Daniel M. Schwartz,. Julie A. Komfield,Robert H. Grubbs, and Christian A. Sandstedt entitled SILICONE IOLSEMBEDDED WITH PHOTO-SENSITIVE COMPOSITIONS; and (iii) U.S. ProvisionalApplication No. 60/140,298 filed Jun. 17, 1999 filed by inventorsJagdish M. Jethinalani, Daniel M. Schwartz, Julie A. Komfield, Robert H.Grubbs, and Christian A. Sandstedt entitled SILICONE IOLS EMBEDDED WITHPHOTOSENSITIVE COMPOSITIONS, all three of which are incorporated hereinby reference in their entireties.

BACKGROUND

Approximately two million cataract surgery procedures are performed inthe United States annually. The procedure generally involves making anincision in the anterior lens capsule to remove the cataractouscrystalline lens and implanting an intraocular lens in its place. Thepower of the implanted lens is selected (based upon pre-operativemeasurements of ocular length and corneal curvature) to enable thepatient to see without additional corrective measures (e.g., glasses orcontact lenses). Unfortunately, due to errors in measurement, and/orvariable lens positioning and wound healing, about half of all patientsundergoing this procedure will not enjoy optimal vision withoutcorrection after surgery. Brandser et al., Acta Ophthalmol Scand75:162-165 (1997); Oshika et al., J cataract Refract Surg 24:509-514(1998). Because the power of prior art intraocular lenses generallycannot be adjusted once they have been implanted, the patient typicallymust choose between replacing the implanted lens with another lens of adifferent power or be resigned to the use of additional correctivelenses such as glasses or contact lenses. Since the benefits typicallydo not outweigh the risks of the former, it is almost never done.

An intraocular lens whose power may be adjusted after implantation andsubsequent wound healing would be an ideal solution to post-operativerefractive errors associated with cataract surgery. Moreover, such alens would have wider applications and may be used to correct moretypical conditions such as myopia, hyperopia, and astigmatism. Althoughsurgical procedures such as LASIK which uses a laser to reshape thecornea are available, only low to moderate myopia and hyperopia may bereadily treated. In contrast, an intraocular lens, which would functionjust like glasses or contact lenses to correct for the refractive errorof the natural eye, could be implanted in the eye of any patient.Because the power of the implanted lens may be adjusted, post-operativerefractive errors due to measurement irregularities and/or variable lenspositioning and wound healing may be fine tuned in-situ.

SUMMARY

The present invention relates to optical elements, particularly medicallenses and methods of using the same. In general, the inventive lenscomprises (i) a first polymer matrix and (ii) a refraction modulatingcomposition that is capable of stimulus-induced polymerization dispersedtherein. In one embodiment, when at least a portion of the lens isexposed to an appropriate stimulus, the refraction modulatingcomposition forms a second polymer matrix, the formation of whichmodifies lens power.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a schematic of a lens of the present invention beingirradiated in the center followed by irradiation of the entire lens to“lock in” the modified lens power.

FIG. 2 illustrates the prism irradiation procedure that is used toquantify the refractive index changes after being exposed to variousamounts of irradiation.

FIG. 3 shows unfiltered moiré fringe patterns of an inventive IOL. Theangle between the two Ronchi rulings was set at 12° and the displacementdistance between the first and second moiré patterns was 4.92 mm.

FIG. 4 is a Ronchigram of an inventive IOL. The Ronchi patterncorresponds to a 2.6 mm central region of the lens.

FIG. 5 is a schematic illustrating a second mechanism whereby theformation of the second polymer matrix modulates a lens property byaltering lens shape.

FIG. 6 are Ronchi interferograms of an IOL before and after lasertreatment depicting approximately a +8.6 diopter change in lens powerwithin the eye. The spacing of alternative light and dark bands isproportional to lens power.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to optical elements (e.g., lenses andprisms) that are capable of post-fabrication power modifications. Moreparticularly, the present invention relates to intraocular lenses whosepower may be adjusted in-situ after implantation in the eye.

The inventive optical elements comprise a first polymer matrix and arefraction modulating composition dispersed therein. The first polymermatrix forms the optical element framework and is generally responsiblefor many of its material properties. The refraction modulatingcomposition (“RMC”) may be a single compound or a combination ofcompounds that is capable of stimulus-induced polymerization, preferablyphoto-polymerization. As used herein, the term “polymerization” refersto a reaction wherein at least one of the components of the refractionmodulating composition reacts to form at least one covalent or physicalbond with either a like component or with a different component. Theidentities of the first polymer matrix and the refraction modulatingcompositions will depend on the end use of the optical element. However,as a general rule, the first polymer matrix and the refractionmodulating composition are selected such that the components thatcomprise the refraction modulating composition are capable of diffusionwithin the first polymer matrix. Put another way, a loose first polymermatrix will tend to be paired with larger RMC components and a tightfirst polymer matrix will tend to be paired with smaller RMC components.

Upon exposure to an appropriate energy source (e.g., heat or light), therefraction modulating composition typically forms a second polymermatrix in the exposed region of the optical element. The presence of thesecond polymer matrix changes the material characteristics of thisportion of the optical element to modulate its refraction capabilities.In general, the formation of the second polymer matrix typicallyincreases the refractive index of the affected portion of the opticalelement. After exposure, the refraction modulating composition in theunexposed region will migrate into the exposed region over time. Theamount of RMC migration into the exposed region is time dependent andmay be precisely controlled. If enough time is permitted, the RMCcomponents will re-equilibrate and redistribute throughout opticalelement (i.e., the first polymer matrix, including the exposed region).When the region is re-exposed to the energy source, the refractionmodulating composition (“RMC”) that has since migrated into the region(which may be less than if the RMC composition were allowed tore-equilibrate) polymerizes to further increase the formation of thesecond polymer matrix. This process (exposure followed by an appropriatetime interval to allow for diffusion) may be repeated until the exposedregion of the optical element has reached the desired property (e.g.,power, refractive index, or shape). At this point, the entire opticalelement is exposed to the energy source to “lock-in” the desired lensproperty by polymerizing the remaining RMC components that are outsidethe exposed region before the components can migrate into the exposedregion. In other words, because freely diffusable RMC components are nolonger available, subsequent exposure of the optical element to anenergy source cannot further change its power. FIG. 1 illustrates oneinventive embodiment, refractive index modulation (thus lens powermodulation) followed by a lock in.

The first polymer matrix is a covalently or physically linked structurethat functions as an optical element and is formed from a first polymermatrix composition (“FPMC”).

In general, the first polymer matrix composition comprises one or moremonomers that upon polymerization will form the first polymer matrix.The first polymer matrix composition optionally may include any numberof formulation auxiliaries that modulate the polymerization reaction orimprove any property of the optical element. Illustrative examples ofsuitable FPMC monomers include acrylics, methacrylates, phosphazenes,siloxanes, vinyls, homopolymers and copolymers thereof. As used herein,a “monomer” refers to any unit (which may itself either be a homopolymeror copolymer) which may be linked together to form a polymer containingrepeating units of the same. If the FPMC monomer is a copolymer, it maybe comprised of the same type of monomers (e.g., two differentsiloxanes) or it may be comprised of different types of monomers (e.g.,a siloxane and an acrylic).

In one embodiment, the one or more monomers that form the first polymermatrix are polymerized and cross-linked in the presence of therefraction modulating composition. In another embodiment, polymericstarting material that forms the first polymer matrix is cross-linked inthe presence of the refraction modulating composition. Under eitherscenario, the RMC components must be compatible with and not appreciablyinterfere with the formation of the first polymer matrix. Similarly, theformation of the second polymer matrix should also be compatible withthe existing first polymer matrix. Put another way, the first polymermatrix and the second polymer matrix should not phase separate and lighttransmission by the optical element should be unaffected.

As described previously, the refraction modulating composition may be asingle component or multiple components so long as: (i) it is compatiblewith the formation of the first polymer matrix; (ii) it remains capableof stimulus-induced polymerization after the formation of the firstpolymer matrix; and (iii) it is freely diffusable within the firstpolymer matrix. In preferred embodiments, the stimulus-inducedpolymerization is photo-induced polymerization.

The inventive optical elements have numerous applications in theelectronics and data storage industries. Another application for thepresent invention is as medical lenses, particularly as intraoculalenses.

In general, there are two types of intraocular lenses (“IOLs”). Thefirst type of an intraocular lens replaces the eye's natural lens. Themost common reason for such a procedure is cataracts. The second type ofintraocular lens supplements the existing lens and functions as apermanent corrective lens. This type of lens (sometimes referred to as aphakic intraocular lens) is implanted in the anterior or posteriorchamber to correct any refractive errors of the eye. In theory, thepower for either type of intraocular lenses required for emmetropia(i.e., perfect focus on the retina from light at infinity) can beprecisely calculated. However, in practice, due to errors in measurementof corneal curvature, and/or variable lens positioning and woundhealing, it is estimated that only about half of all patients undergoingIOL implantation will enjoy the best possible vision without the needfor additional correction after surgery. Because prior art IOLs aregenerally incapable of post-surgical power modification, the remainingpatients must resort to other types of vision correction such asexternal lenses (e.g., glasses or contact lenses) or cornea surgery. Theneed for these types of additional corrective measures is obviated withthe use of the intraocular lenses of the present invention.

The inventive intraocular lens comprises a first polymer matrix and arefraction modulating composition dispersed therein. The first polymermatrix and the refraction modulating composition are as described abovewith the additional requirement that the resulting lens bebiocompatible.

Illustrative examples of a suitable first polymer matrix include:poly-acrylates such as poly-alkyl acrylates and poly-hydroxyalkylacrylates; poly-methacrylates such as poly-methyl methacrylate (“PMMA”),poly-hydroxyethyl methacrylate (“PHEMA”), and poly-hydroxypropylmethacrylate (“HPMA”); poly-vinyls such as poly-styrene andpoly-vinylpyrrolidone (“PNVP”); poly-siloxanes such aspoly-dimethylsiloxane; poly-phosphazenes, and copolymers of thereof U.S.Pat. No.4,260,725 and patents and references cited therein (which areall incorporated herein by reference) provide more specific examples ofsuitable polymers that may be used to form the first polymer matrix.

In preferred embodiments, the first polymer matrix generally possesses arelatively low glass transition temperature (“T_(g)”) such that theresulting IOL tends to exhibit fluid-like and/or elastomeric behavior,and is typically formed by crosslinking one or more polymeric startingmaterials wherein each polymeric starting material includes at least onecrosslinkable group. Illustrative examples of suitable crosslinkablegroups include but are not limited to hydride, acetoxy, alkoxy, amino,anhydride, aryloxy, carboxy, enoxy, epoxy, halide, isocyano, olefinic,and oxime. In more preferred embodiments, each polymeric startingmaterial includes terminal monomers (also referred to as endcaps) thatare either the same or different from the one or more monomers thatcomprise the polymeric starting material but include at least onecrosslinkable group. In other words, the terminal monomers begin and endthe polymeric starting material and include at least one crosslinkablegroup as part of its structure. Although it is not necessary for thepractice of the present invention, the mechanism for crosslinking thepolymeric starting material preferably is different than the mechanismfor the stimulus-induced polymerization of the components that comprisethe refraction modulating composition. For example, if the refractionmodulating composition is polymerized by photo-induced polymerization,then it is preferred that the polymeric starting materials havecrosslinkable groups that are polymerized by any mechanism other thanphoto-induced polymerization.

An especially preferred class of polymeric starting materials for theformation of the first polymer matrix is poly-siloxanes (also known as“silicones”) endcapped with a terminal monomer which includes acrosslinkable group selected from the group consisting of acetoxy,amino, alkoxy, halide, hydroxy, and mercapto. Because silicone IOLs tendto be flexible and foldable, generally smaller incisions may be usedduring the IOL implantation procedure. An example of an especiallypreferred polymeric starting material isbis(diacetoxymethylsilyl)-polydimethylsiloxane (which ispoly-dimethylsiloxane that is endcapped with a diacetoxymethylsilylterminal monomer).

The refraction modulating composition that is used in fabricating IOLsis as described above except that it has the additional requirement ofbiocompatibility.

The refraction modulating composition is capable of stimulus-inducedpolymerization and may be a single component or multiple components solong as: (i) it is compatible with the formation of the first polymermatrix; (ii) it remains capable of stimulus-induced polymerization afterthe formation of the first polymer matrix; and (iii) it is freelydiffusable within the first polymer matrix. In general, the same type ofmonomers that is used to form the first polymer matrix may be used as acomponent of the refraction modulating composition. However, because ofthe requirement that the RMC monomers must be diffusable within thefirst polymer matrix, the RMC monomers generally tend to be smaller(i.e., have lower molecular weights) than the monomers which form thefirst polymer matrix. In addition to the one or more monomers, therefraction modulating composition may include other components such asinitiators and sensitizers that facilitate the formation of the secondpolymer matrix.

In preferred embodiments, the stimulus-induced polymerization isphoto-polymerization. In other words, the one or more monomers thatcomprise the refraction modulating composition each preferably includesat least one group that is capable of photopolymerization. Illustrativeexamples of such photopolymerizable groups include but are not limitedto acrylate, allyloxy, cinnamoyl, methacrylate, stibenyl, and vinyl. Inmore preferred embodiments, the refraction modulating compositionincludes a photoinitiator (any compound used to generate free radicals)either alone or in the presence of a sensitizer. Examples of suitablephotoinitiators include acetophenones (e.g., a-substitutedhaloacetophenones, and diethoxyacetophenone);2,4-dichloromethyl-1,3,5-triazines; benzoin methyl ether; and o-benzoyloximino ketone. Examples of suitable sensitizers includep-(dialkylamino)aryl aldehyde; N-alkylindolylidene; andbis[p-(dialkylarnino)benzylidene] ketone.

Because of the preference for flexible and foldable IOLs, an especiallypreferred class of RMC monomers is poly-siloxanes endcapped with aterminal siloxane moiety that includes a photopolymnerizable group. Anillustrative representation of such a monomer is

X—Y—x¹

wherein Y is a siloxane which may be a monomer, a homopolymer or acopolymer formed from any number of siloxane units, and X and X¹ may bethe same or different and are each independently a terminal siloxanemoiety that includes a photopolymerizable group. An illustrative exampleof Y include

wherein:

m and n are independently each an integer and

R¹, R², R³, and R⁴ are independently each hydrogen, alkyl (primary,secondary, tertiary, cyclo), aryl, or heteroaryl. In preferredembodiments, R¹, R², R³, and R⁴ is a C₁-C₁₀ alkyl or phenyl. Because RMCmonomers with a relatively high aryl content have been found to producelarger changes in the refractive index of the inventive lens, it isgenerally preferred that at least one of R¹, R², R³, and R⁴ is an aryl,particularly phenyl. In more preferred embodiments, R¹, R², and R³ arethe same and are methyl, ethyl or propyl and R⁴ is phenyl.

Illustrative examples of X and X¹ (or X¹ and X depending on how the RMCpolymer is depicted) are

respectively wherein:

R⁵ and R⁶ are independently each hydrogen, alkyl, aryl, or heteroaryl;and

Z is a photopolymerizable group.

In preferred embodiments, R⁵ and R⁶ are independently each a C₁-C₁₀alkyl or phenyl and Z is a photopolymerizable group that includes amoiety selected from the group consisting of acrylate, allyloxy,cinnamoyl, methacrylate, stibenyl, and vinyl. In more preferredembodiments, R⁵ and R⁶ is methyl, ethyl, or propyl and Z is aphotopolymerizable group that includes an acrylate or methacrylatemoiety.

In especially preferred embodiments, an RMC monomer is of the followingformula

wherein X and X¹ are the same and R¹, R², R¹, and R⁴ are as definedpreviously.

Illustrative examples of such RMC monomers includedimethylsiloxane-diphenylsiloxane copolymer endcapped with a vinyldimethylsilane group; dimethylsiloxane-methylphenylsiloxane copolymerendcapped with a methacryloxypropyl dimethylsilane group; anddimethylsiloxane endcapped with a methacryloxypropyldimethylsilanegroup.

Although any suitable method may be used, a ring-opening reaction of oneor more cyclic siloxanes in the presence of triflic acid has been foundto be a particularly efficient method of making one class of inventiveRMC monomers. Briefly, the method comprises contacting a cyclic siloxanewith a compound of the formula

in the presence of triflic acid wherein R⁵, R⁶, and Z are as definedpreviously. The cyclic siloxane may be a cyclic siloxane monomer,homopolymer, or copolymer. Alternatively, more than one cyclic siloxanemay be used. For example, a cyclic dimethylsiloxane tetramer and acyclic methyl-phenylsiloxane trimer are contacted withbis-methacryloxypropyltetramethyldisiloxane in the presence of triflicacid to form a dimethyl-siloxane methyl-phenylsiloxane copolymer that isendcapped with a methacryloxylpropyl-dimethylsilane group, an especiallypreferred RMC monomer.

The inventive IOLs may be fabricated with any suitable method thatresults in a first polymer matrix with one or more components whichcomprise the refraction modulating composition dispersed therein, andwherein the refraction modulating composition is capable ofstimulus-induced polymerization to form a second polymer matrix. Ingeneral, the method for making an inventive IOL is the same as that formaking an inventive optical element. In one embodiment, the methodcomprises

mixing a first polymer matrix composition with a refraction modulatingcomposition to form a reaction mixture;

placing the reaction mixture into a mold;

polymerizing the first polymer matrix composition to form said opticalelement; and,

removing the optical element from the mold.

The type of mold that is used will depend on the optical element beingmade. For example, if the optical element is a prism, then a mold in theshape of a prism is used. Similarly, if the optical element is anintraocular lens, then an intraocular lens mold is used and so forth. Asdescribed previously, the first polymer matrix composition comprises oneor more monomers for forming the first polymer matrix and optionallyincludes any number of formulation auxiliaries that either modulate thepolymerization reaction or improve any property (whether or not relatedto the optical characteristic) of the optical element. Similarly, therefraction modulating composition comprises one or more components thattogether are capable of stimulus-induced polymerization to form thesecond polymer matrix. Because flexible and foldable intraocular lensesgenerally permit smaller incisions, it is preferred that both the firstpolymer matrix composition and the refraction modulating compositioninclude one or more silicone-based or low T_(g) acrylic monomers whenthe inventive method is used to make IOLs.

A key advantage of the intraocular lens of the present invention is thatan IOL property may be modified after implantation within the eye. Forexample, any errors in the power calculation due to imperfect cornealmeasurements and/or variable lens positioning and wound healing may bemodified in a post surgical outpatient procedure.

In addition to the change in the IOL refractive index, thestimulus-induced formation of the second polymer matrix has been foundto affect the IOL power by altering the lens curvature in a predictablemanner. As a result, both mechanisms may be exploited to modulate an IOLproperty, such as power, after it has been implanted within the eye. Ingeneral, the method for implementing an inventive IOL having a firstpolymer matrix and a refraction modulating composition dispersedtherein, comprises:

(a) exposing at least a portion of the lens to a stimulus whereby thestimulus induces the polymerization of the refraction modulatingcomposition.

If after implantation and wound healing, no IOL property needs to bemodified, then the exposed portion is the entire lens. The exposure ofthe entire lens will lock in the then existing properties of theimplanted lens.

However, if a lens characteristic such as its power needs to bemodified, then only a portion of the lens (something less than theentire lens) would be exposed. In one embodiment, the method ofimplementing the inventive IOL farther comprises:

(b) waiting an interval of time; and

(c) re-exposing the portion of the lens to the stimulus.

This procedure generally will induce the further polymerization of therefraction modulating composition within the exposed lens portion. Steps(b) and (c) may be repeated any number of times until the intraocularlens (or optical element) has reached the desired lens characteristic.At this point, the method may further include the step of exposing theentire lens to the stimulus to lock-in the desired lens property.

In another embodiment wherein a lens property needs to be modified, amethod for implementing an inventive IOL comprises:

(a) exposing a first portion of the lens to a stimulus whereby thestimulus induces the polymerization of the refraction modulatingcomposition; and

(b) exposing a second portion of the lens to the stimulus.

The first lens portion and the second lens portion represent differentregions of the lens although they may overlap. Optionally, the methodmay include an interval of time between the exposures of the first lensportion and the second lens portion. In addition, the method may furthercomprise re-exposing the first lens portion and/or the second lensportion any number of times (with or without an interval of time betweenexposures) or may further comprise exposing additional portions of thelens (e.g., a third lens portion, a fourth lens portion, etc.). Once thedesired property has been reached, then the method may further includethe step of exposing the entire lens to the stimulus to lock-in thedesired lens property.

In general, the location of the one or more exposed portions will varydepending on the type of refractive error being corrected. For example,in one embodiment, the exposed portion of the IOL is the optical zonewhich is the center region of the lens (e.g., between about 4 mm andabout 5 mm in diameter). Alternatively, the one or more exposed lensportions may be along IOL's outer rim or along a particular meridian. Inpreferred embodiments, the stimulus is light. In more preferredembodiments, the light is from a laser source.

In summary, the present invention relates to a novel optical elementthat comprises (i) a first polymer matrix and (ii) a refractionmodulating composition that is capable of stimulus-inducedpolymerization dispersed therein. When at least a portion of the opticalelement is exposed to an appropriate stimulus, the refraction modulatingcomposition forms a second polymer matrix. The amount and location ofthe second polymer matrix modifies a property such as the power of theoptical element by changing its refractive index and/or by altering itsshape.

EXAMPLE 1

Materials comprising various amounts of (a) poly-dimethylsiloxaneendcapped with diacetoxymethylsilane (“PDMS”) (36000 g/mol), (b)dimethylsiloxane-diphenylsiloxane copolymer endcapped withvinyl-dimethyl silane (“DMDPS”) (15,500 g/mol), and (c) aUV-photoinitiator, 2,2-dimethoxy-2-phenylacetophenone (“DMPA”) as shownby Table 1 were made and tested. PDMS is the monomer which forms firstpolymer matrix, and DMDPS and DMPA together comprise the refractionmodulating composition.

TABLE 1 PDMS (wt. %) DMDPS (wt. %) DMPA (wt. %)^(a) 1 90 10 1.5 2 80 201.5 3 75 25 1.5 4 70 30 1.5 ^(a)wt % with respect to DMDPS.

Briefly, appropriate amounts of PMDS (Gelest DMS-D33; 36000 g/mol),DMDPS (Gelest PDV-0325; 3.0-3.5 mole % diphenyl, 15,500 g/mol), and DMPA(Acros; 1.5 wt % with respect to DMDPS) were weighed together in analuminum pan, manually mixed at room temperature until the DMPAdissolved, and degassed under pressure (5 mtorr) for 2-4 minutes toremove air bubbles. Photosensitive prisms were fabricated by pouring theresulting silicone composition into a mold made of three glass slidesheld together by scotch tape in the form of a prism and sealed at oneend with silicone caulk. The prisms are ˜5 cm long and the dimensions ofthe three sides are ˜8 mm each. The PDMS in the prisms was moisturecured and stored in the dark at room temperature for a period of 7 daysto ensure that the resulting first polymer matrix was non-tacky, clear,and transparent.

The amount of photoinitiator (1.5 wt. %) was based on prior experimentswith fixed RMC monomer content of 25% in which the photoinitiatorcontent was varied. Maximal refractive index modulation was observed forcompositions containing 1.5% and 2 wt. % photoinitiator while saturationin refractive index occurred at 5 wt. %.

EXAMPLE 2

Synthesis RMC Monomers

As illustrated by Scheme 1, commercially available cyclicdimethylsiloxane tetramer (“D₄”), cyclic methylphenylsiloxane trimer(“D₃′”) in various ratios were ring-opened by triflic acid andbis-methacryloxylpropyltetramethyldisiloxane (“MPS”) were reacted in aone pot synthesis. U.S. Pat. No. 4,260,725; Kunzler, J. F., Trends inPolymer Science, 4: 52-59 (1996); Kunzler et al. J. Appl. Poly. Sci.,55: 611-619 (1995); and Lai et al., J. Poly. Sci. A. Poly. Chem., 33:1773-1782 (1995).

Briefly, appropriate amounts of MPS, D₄, and D₃′ were stirred in a vialfor 1.5-2 hours. An appropriate amount of triflic acid was added and theresulting mixture was stirred for another 20 hours at room temperature.The reaction mixture was diluted with hexane, neutralized (the acid) bythe addition of sodium bicarbonate, and dried by the addition ofanhydrous sodium sulfate. After filtration and rotovaporation of hexane,the RMC monomer was purified by further filtration through an activatedcarbon column. The RMC monomer was dried at 5 mtorr of pressure between70-80 ° C. for 12-18 hours.

The amounts of phenyl, methyl, and endgroup incorporation werecalculated from ¹H-NMR spectra that were run in deuterated chloroformwithout internal standard tetramethylsilane (“TMS”). Illustrativeexamples of chemical shifts for some of the synthesized RMC monomersfollows. A 1000 g/mole RMC monomer containing 5.58 mole % phenyl (madeby reacting: 4.85 g (12.5 mmole) of MPS; 1.68 g (4.1 mmole) of D₃′; 5.98g (20.2 mmole) of D₄; and 108 μl (1.21 mmole) of triflic acid:δ=7.56-7.5 ppm (m, 2H) aromatic, δ=7.32-7.33 ppm (m, 3H) aromatic,δ=6.09 ppm (d, 2H) olefinic, δ=5.53 ppm (d, 2H) olefinic, δ=4.07-4.10ppm (t, 4H) —O—CH ₂CH₂CH₂—, δ=1.93 ppm (s, 6H) methyl of methacrylate,δ=1.65-1.71 ppm (m, 4H) —O—CH₂CH ₂CH₂—, δ=0.54-0.58 ppm (m, 4H)—O—CH₂CH₂CH ₂—Si, δ=0.29-0.30 ppm (d, 3H), CH ₃—Si-Phenyl, δ=0.04-0.08ppm (s, 50 H) (CH ₃)₂Si of the backbone.

A 2000 g/mole RMC monomer containing 5.26 mole % phenyl (made byreacting: 2.32 g (6.0 mmole) of MPS; 1.94 g (4.7 mmole) of D₃′; 7.74 g(26.1 mmole) of D₄; and 136 μl (1.54 mmole) of triflic acid: δ=7.54-7.58ppm (m, 4H) aromatic, δ=7.32-7.34 ppm (m, 6H) aromatic, δ=6.09 ppm (d,2H) olefinic, δ=5.53 ppm (d, 2H) olefinic, δ=4.08-4.11 ppm (t, 4H) —O—CH₂CH₂CH₂—, δ=1.94 ppm (s, 6H) methyl of methacrylate, δ=1.67-1.71 ppm (m,4H) —O—CH₂CH ₂CH₂—, δ=0.54-0.59 ppm (m, 4H) —O—CH₂CH₂CH ₂—Si,δ=0.29-0.31 ppm (m, 6H), CH ₃-Si-Phenyl, δ=0.04-0.09 ppm (s, 112H) (CH₃)₂Si of the backbone.

A 4000 g/mole RMC monomer containing 4.16 mole % phenyl (made byreacting: 1.06 g (2.74 mmole) of MPS; 1.67 g (4.1 mmole) of D₃′; 9.28 g(31.3 mmole) of D₄; and 157 μl (1.77 mmole) of triflic acid: δ=7.57-7.60ppm (m, 8H) aromatic, δ=7.32-7.34 ppm (m, 6H) aromatic, δ=6.10 ppm (d,2H) olefinic, δ=5.54 ppm (d, 2H) olefinic, δ=4.08-4.12 ppm (t, 4H)—O—CHhd 2CH₂CH₂—, δ=1.94 ppm (s, 6H) methyl of methacrylate, δ=1.65-1.74ppm (m, 4H) —O—CH₂CH ₂CH₂—, δ=0.55-0.59 ppm (m, 4H) —O—CH₂CH ₂—Si,δ=0.31 ppm (m, 11H), CH ₃-Si-Phenyl, δ=0.07-0.09 ppm (s, 272 H) (CH₃)₂Si of the backbone.

Similarly, to synthesize dimethylsiloxane polymer without anymethylphenylsiloxane units and endcapped with methyacryloxypropyldimethylsilane, the ratio of D₄ to MPS was varied without incorporatingD′₃.

Molecular weights were calculated by ¹H-NMR and by gel permeationchromatography (“GPC”). Absolute molecular weights were obtained byuniversal calibration method using polystyrene and poly(methylmethacrylate) standards. Table 2 shows the characterization of other RMCmonomers synthesized by the triflic acid ring opening polymerization.

TABLE 2 Mole % Mole % Mole % Mn Mn Phenyl Methyl Methacrylate (NMR)(GPC) n_(D) A 6.17 87.5 6.32 1001 946 1.44061 B 3.04 90.8 6.16 985 7161.43188 C 5.26 92.1 2.62 1906 1880 — D 4.16 94.8 1.06 4054 4200 1.42427E 0 94.17 5.83 987 1020 1.42272 F 0 98.88 1.12 3661 4300 1.40843

At 10-40 wt %, these RMC monomers of molecular weights 1000 to 4000g/mol with 3-6.2 mole % phenyl content are completely miscible,biocompatible, and form optically clear prisms and lenses whenincorporated in the silicone matrix. RMC monomers with high phenylcontent (4-6 mole %) and low molecular weight (1000-4000 g/mol) resultedin increases in refractive index change of 2.5 times and increases inspeeds of diffusion of 3.5 to 5.0 times compared to the RMC monomer usedin Table 1 (dimethylsiloxane-diphenylsiloxane copolymer endcapped withvinyldimethyl silane (“DMDPS”) (3-3.5 mole % diphenyl content, 15500g/mol). These RMC monomers were used to make optical elementscomprising: (a) poly-dimethylsiloxane endcapped withdiacetoxymethylsilane (“PDMS”) (36000 g/mol), (b) dimethylsiloxanemethylphenylsiloxane copolymer that is endcapped with amethacryloxylpropyldimethylsilane group, and (c)2,2-dirnethoxy-2-phenylacetophenone (“DMPA”). Note that component (a) isthe monomer that forms the first polymer matrix and components (b) and(c) comprise the refraction modulating composition.

EXAMPLE 3

Fabrication of intraocular lenses (“IOL”)

An intraocular mold was designed according to well-accepted standards.See e.g., U.S. Pat. Nos. 5,762,836; 5,141,678; and 5,213,825. Briefly,the mold is built around two plano-concave surfaces possessing radii ofcurvatures of −6.46 mm and/or −12.92 mm, respectively. The resultinglenses are 6.35 mm in diameter and possess a thickness ranging from 0.64mm, 0.98 mm, or 1.32 mm depending upon the combination of concave lenssurfaces used. Using two different radii of curvatures in their threepossible combinations and assuming a nominal refractive index of 1.404for the IOL composition, lenses with pre-irradiation powers of 10.51 D(62.09 D in air), 15.75 D (92.44 in air), and 20.95 D (121.46 D in air)were fabricated.

EXAMPLE 4

Stability of Compositions against Leaching

Three IOLs were fabricated with 30 and 10 wt % of RMC monomers B and Dincorporated in 60 wt % of the PDMS matrix. After moisture curing ofPDMS to form the first polymer matrix, the presence of any free RMCmonomer in the aqueous solution was analyzed as follows. Two out ofthree lenses were irradiated three times for a period of 2 minutes using340 nm light, while the third was not irradiated at all. One of theirradiated lenses was then locked by exposing the entire lens matrix toradiation. All three lenses were mechanically shaken for 3 days in 1.0 MNaCl solution. The NaCl solutions were then extracted by hexane andanalyzed by ¹H-NMR. No peaks due to the RMC monomer were observed in theNMR spectrum. These results suggest that the RMC monomers did not leachout of the matrix into the aqueous phase in all three cases. Earlierstudies on a vinyl endcapped silicone RMC monomer showed similar resultseven after being stored in 1.0 M NaCl solution for more than one year.

EXAMPLE 5

Toxicological Studies in Rabbit Eyes

Sterilized, unirradiated and irradiated silicone IOLs (fabricated asdescribed in Example 3) of the present invention and a sterilizedcommercially available silicone IOL were implanted in albino rabbiteyes. After clinically following the eyes for one week, the rabbits weresacrificed. The extracted eyes were enucleated, placed in formalin andstudied histopathologically. There is no evidence of corneal toxicity,anterior segment inflammation, or other signs of lens toxicity.

EXAMPLE 6

Irradiation of Silicone Prisms

Because of the ease of measuring refractive index change (An) andpercent net refractive index change (% Δn) of prisms, the inventiveformulations were molded into prisms for irradiation andcharacterization. Prisms were fabricated by mixing and pouring (a) 90-60wt % of high Mn PDMS, (b) 10-40 wt % of RMC monomers in Table 2, and (c)0.75 wt % (with respect to the RMC monomers) of the photoinitiator DMPAinto glass molds in the form of prisms 5 cm long and 8.0 mm on eachside. The silicone composition in the prisms was moisture cured andstored in the dark at room temperature for a period of 7 days to ensurethat the final matrix was non-tacky, clear and transparent.

Two of the long sides of each prism were covered by a black backgroundwhile the third was covered by a photomask made of an aluminum platewith rectangular windows (2.5 mm×10 mm). Each prism was exposed to aflux of 1.2 mW/cm² of a collimated 340 nm light (peak absorption of thephotoinitiator) from a 1000 W Xe:Hg arc lamp for various time periods.The ANSI guidelines indicate that the maximum permissible exposure(“MPE”) at the retina using 340 nm light for a 10-30000 s exposure is1000 mJ/cm². Criteria for Exposure of Eye and Skin. American NationalStandard Z136.1: 31-42 (1993). The single dose intensity 1.2 mW/cm² of340 nm light for a period of 2 minutes corresponds to 144 mJ/cm² whichis well within the ANSI guidelines. In fact, even the overall intensityfor three exposures (432 mJ/cm²) is well within the ANSI guidelines.FIG. 2 is an illustration of the prism irradiation procedure.

The prisms were subject to both (i) continuous irradiation—one-timeexposure for a known time period, and (ii) “staccato” irradiation—threeshorter exposures with long intervals between them. During continuousirradiation, the refractive index contrast is dependent on thecrosslinking density and the mole % phenyl groups, while in theinterrupted irradiation, RMC monomer diffusion and further crosslinkingalso play an important role. During staccato irradiation, the RMCmonomer polymerization depends on the rate of propagation during eachexposure and the extent of interdiffusion of free RMC monomer during theintervals between exposures. Typical values for the diffusioncoefficient of oligomers (similar to the 1000 g/mole RMC monomers usedin the practice of the present invention) in a silicone matrix are onthe order of 10⁻⁶ to 10⁻⁷ cm²/s. In other words, the inventive RMCmonomers require approximately 2.8 to 28 hours to diffuse 1 mm (roughlythe half width of the irradiated bands). The distance of a typicaloptical zone in an IOL is about 4 to about 5 mm across. However, thedistance of the optical zone may also be outside of this range. Afterthe appropriate exposures, the prisms were irradiated without thephotomask (thus exposing the entire matrix) for 6 minutes using a mediumpressure mercury-arc lamp. This polymerized the remaining silicone RMCmonomers and thus “locked” the refractive index of the prism in place.Notably, the combined total irradiation of the localized exposures andthe “lock-in” exposure was still within ANSI guidelines.

EXAMPLE 7

Prism Dose Response Curves

Inventive prisms fabricated from RMC monomers described by Table 2 weremasked and initially exposed for 0.5, 1, 2, 5, and 10 minutes using 1.2mW/cm² of the 340 nm line from a 1000 W Xe:Hg arc lamp. The exposedregions of the prisms were marked, the mask detached and the refractiveindex changes measured. The refractive index modulation of the prismswas measured by observing the deflection of a sheet of laser lightpassed through the prism. The difference in deflection of the beampassing through the exposed and unexposed regions was used to quantifythe refractive index change (Δn) and the percentage change in therefractive index (% Δn).

After three hours, the prisms were remasked with the windows overlappingwith the previously exposed regions and irradiated for a second time for0.5, 1, 2, and 5 minutes (total time thus equaled 1, 2, 4, and 10minutes respectively). The masks were detached and the refractive indexchanges measured. After another three hours, the prisms were exposed athird time for 0.5, 1, and 2 minutes (total time thus equaled 1.5, 3,and 6 minutes) and the refractive index changes were measured. Asexpected, the % Δn increased with exposure time for each prism aftereach exposure resulting in prototypical dose response curves. Based uponthese results, adequate RMC monomer diffusion appears to occur in about3 hours for 1000 g/mole RMC monomer.

All of the RMC monomers (B-F) except for RMC monomer A resulted inoptically clear and transparent prisms before and after their respectiveexposures. For example, the largest % Δn for RMC monomers B, C, and D at40 wt % incorporation into 60 wt % FPMC were 0.52%, 0.63% and 0.30%respectively which corresponded to 6 minutes of total exposure (threeexposures of 2 minutes each separated by 3 hour intervals for RMCmonomer B and 3 days for RMC monomers C and D). However, although itproduced the largest change in refractive index (0.95%), the prismfabricated from RMC monomer A (also at 40 wt % incorporation into 60 wt% FPMC and 6 minutes of total exposure—three exposures of 2 minutes eachseparated by 3 hour intervals) turned somewhat cloudy. Thus, if RMCmonomer A were used to fabricate an IOL, then the RMC must include lessthan 40 wt % of RMC monomer A or the % Δn must be kept below the pointwhere the optical clarity of the material is compromised.

A comparison between the continuous and staccato irradiation for RMC Aand C in the prisms shows that lower % Δn values occurs in prismsexposed to continuous irradiation as compared to those observed usingstaccato irradiations. As indicated by these results, the time intervalbetween exposures (which is related to the amount of RMC diffusion fromthe unexposed to exposed regions) may be exploited to precisely modulatethe refractive index of any material made from the inventive polymercompositions.

Exposure of the entire, previously irradiated prisms to a mediumpressure Hg arc lamp polymerized any remaining free RMC, effectivelylocking the refractive index contrast. Measurement of the refractiveindex change before and after photolocking indicated no furthermodulation in the refractive index.

EXAMPLE 8

Optical Characterization of IOLs

Talbot interferometry and the Ronchi test were used to qualitatively andquantitatively measure any primary optical aberrations (primaryspherical, coma, astigmatism, field curvature, and distortion) presentin pre- and post-irradiated lenses as well as quantifying changes inpower upon photopolymerization.

In Talbot interferometry, the test IOL is positioned between the twoRonchi rulings with the second grating placed outside the focus of theIOL and rotated at a known angle, θ, with respect to the first grating.Superposition of the autoimage of the first Ronchi ruling (p₁=300lines/inch) onto the second grating (P₂=150 lines/inch) produces moiréfringes inclined at an angle, α₁. A second moiré fringe pattern isconstructed by axial displacement of the second Ronchi ruling along theoptic axis a known distance, d, from the test lens. Displacement of thesecond grating allows the autoimage of the first Ronchi ruling toincrease in magnification causing the observed moiré fringe pattern torotate to a new angle, α₂. Knowledge of moiré pitch angles permitsdetermination of the focal length of the lens (or inversely its power)through the expression:$f = {\frac{p_{1}}{p_{2}}{{d\left( {\frac{1}{{\tan \quad \alpha_{2}\sin \quad \theta} + {\cos \quad \theta}} - \frac{1}{{\tan \quad \alpha_{1}\sin \quad \theta} + {\cos \quad \theta}}} \right)}^{- 1}.}}$

To illustrate the applicability of Talbot interferometry to this work,moiré fringe patterns of one of the inventive, pre-irradiated IOLs (60wt % PDMS, 30 wt % RMC monomer B, wt % RMC monomer D, and 0.75% DMPArelative to the two RMC monomers) measured in air is presented in FIG.3. Each of the moiré fringes was fitted with a least squares fittingalgorithm specifically designed for the processing of moire patterns.The angle between the two Ronchi rulings was set at 12°, thedisplacement between the second Ronchi ruling between the first andsecond moiré fringe patterns was 4.92 mm, and the pitch angles of themoiré fringes, measured relative to an orthogonal coordinate systemdefined by the optic axis of the instrument and crossing the two Ronchirulings at 90°, were α₁, =−33.2°±0.30° and α₂=−52.7°±0.40°. Substitutionof these above equation results in a focal length of 10.71±0.50 mm(power=93.77±4.6 D).

Optical aberrations of the inventive IOLs (from either fabrication orfrom the stimulus-induced polymerization of the RMC components) weremonitored using the “Ronchi Test” which involves removing the secondRonchi ruling from the Talbot interferometer and observing the magnifiedautoimage of the first Ronchi ruling after passage though the test IOL.The aberrations of the test lens manifest themselves by the geometricdistortion of the fringe system (produced by the Ronchi ruling) whenviewed in the image plane. A knowledge of the distorted image revealsthe aberration of the lens. In general, the inventive fabricated lenses(both pre and post irradiation treatments) exhibited sharp, parallel,periodic spacing of the interference fringes indicating an absence ofthe majority of primary-order optical aberrations, high optical surfacequality, homogeneity of n in the bulk, and constant lens power. FIG. 4is an illustrative example of a Ronchigram of an inventive,pre-irradiated IOL that was fabricated from 60 wt % PDMS, 30 wt % RMCmonomer B, 10 wt % RMC monomer D, and 0.75% of DMPA relative to the 2RMC monomers.

The use of a single Ronchi ruling may also be used to measure the degreeof convergence of a refracted wavefront (i.e., the power). In thismeasurement, the test IOL is placed in contact with the first Ronchiruling, collimated light is brought incident upon the Ronchi ruling, andthe lens and the magnified autoimage is projected onto an observationscreen. Magnification of the autoimage enables measurement of thecurvature of the refracted wavefront by measuring the spatial frequencyof the projected fringe pattern. These statements are quantified by thefollowing equation:$P_{V} = {\frac{1000}{L}\left( {1 + \frac{d_{s}}{d}} \right)}$

wherein PV is the power of the lens expressed in diopters, L is thedistance from the lens to the observing plane, d_(s), is the magnifiedfringe spacing of the first Ronchi ruling, and d is the original gratingspacing.

EXAMPLE 9

Power changes from Photopolymerization of the Inventive IOLs

An inventive IOL was fabricated as described by Example 3 comprising 60wt % PDMS (n_(D)=1.404), 30 wt % of RMC monomer B (n_(D)=1.4319), 10 wt% of RMC monomer D (n_(D)=1.4243), and 0.75 wt % of the photoinitiatorDMPA relative to the combined weight percents of the two RMC monomers.The IOL was fitted with a 1 mm diameter photomask and exposed to 1.2mW/cm² of 340 nm collimated light from a 1000 W Xe:Hg arc lamp for twominutes. The irradiated lens was then placed in the dark for three hoursto permit polymerization and RMC monomer diffusion. The IOL wasphotolocked by continuously exposing the entire for six minutes usingthe aforementioned light conditions. Measurement of the moire pitchangles followed by substitution into equation 1 resulted in a power of95.1±2.9 D (f=10.52±0.32 mm) and 104.1±3.6 D (f=9.61 mm±0.32 mm) for theunirradiated and irradiated zones, respectively.

The magnitude of the power increase was more than what was predictedfrom the prism experiments where a 0.6% increase in the refractive indexwas routinely achieved. If a similar increase in the refractive indexwas achieved in the IOL, then the expected change in the refractiveindex would be 1.4144 to 1.4229. Using the new refractive index (1.4229)in the calculation of the lens power (in air) and assuming thedimensions of the lens did not change upon photopolymerization, a lenspower of 96.71 D (f=10.34 mm) was calculated. Since this value is lessthan the observed power of 104.1±3.6 D, the additional increase in powermust be from another mechanism.

Further study of the photopolymerized IOL showed that subsequent RMCmonomer diffusion after the initial radiation exposure leads to changesin the radius of curvature of the lens. See e.g., FIG. 5. The RMCmonomer migration from the unradiated zone into the radiated zone causeseither or both of anterior and posterior surfaces of the lens to swellthus changing the radius of curvature of the lens. It has beendetermined that a 7% decrease in the radius of curvature for bothsurfaces is sufficient to explain the observed increase in lens power.

The concomitant change in the radius of curvature was further studied.An identical IOL described above was fabricated. A Ronchi interferogramof the IOL is shown in FIG. 6a (left interferogram). Using a Talbotinterferometer, the focal length of the lens was experimentallydetermined to be 10.52±0.30 mm (95.1±2.8 D). The IOL was then fittedwith a Inmm photomask and irradiated with 1.2 mW/cm² of 340 collimatedlight from a 1000 W Xe:Hg arc lamp continuously for 2.5 minutes. Unlikethe previous IOL, this lens was not “locked in” three hours afterirradiation. FIG. 6b (right interferogram) is the Ronchi interferogramof the lens taken six days after irradiation. The most obvious featurebetween the two interference patterns is the dramatic increase in thefringe spacing, which is indicative of an increase in the refractivepower of the lens.

Measurement of the fringe spacings indicates an increase ofapproximately +38 diopters in air (f≈7.5 mm). This corresponds to achange in the order of approximately +8.6 diopters in the eye. Sincemost post-operative corrections from cataract surgery are within 2diopters, this experiment indicates that the use of the inventive IOLSwill permit a relatively large therapeutic window.

EXAMPLE 10

Photopolymerization studies of non-phenyl-containing IOLs

Inventive IOLs containing non-phenyl containing RMC monomers werefabricated to further study the swelling from the formation of thesecond polymer matrix. An illustrative example of such an IOL wasfabricated from 60 wt % PDMS, 30 wt % RMC monomer E, 10 wt % RMC monomerF, and 0.75% DMPA relative to the two RMC monomers. The pre-irradiationfocal length of the resulting IOL was 10.76 mm (92.94±2.21 D).

In this experiment, the light source was a 325 nm laser line from aHe:Cd laser. A 1 mm diameter photomask was placed over the lens andexposed to a collimated flux of 0.75 mW/cm² at 325 nm for a period oftwo minutes. The lens was then placed in the dark for three hours.Experimental measurements indicated that the focal length of the IOLchanged from 10.76 mm±0.25 mm (92.94 D±2.21 D) to 8.07 mm±0.74 mm(123.92 D±10.59 D) or a dioptric change of +30.98 D±10.82 D in air. Thiscorresponds to an approximate change of +6.68 D in the eye. The amountof irradiation required to induce these changes is only 0.09 J/cm², avalue well under the ANSI maximum permissible exposure (“MPE”) level of1.0 J/cm².

EXAMPLE 11

Monitoring for Potential IOL Changes from Ambient Light

The optical power and quality of the inventive IOLs were monitored toshow that handling and ambient light conditions do not produce anyunwanted changes in lens power. A 1 mm open diameter photomask wasplaced over the central region of an inventive IOL (containing 60 wt %PDMS, 30 wt % RMC monomer E, 10 wt % RMC momnomer F, and 0.75 wt % DMPArelative to the two RMC monomers), exposed to continuous room light fora period of 96 hours, and the spatial frequency of the Ronchi patternsas well as the moiré fringe angles were monitored every 24 hours. Usingthe method of moiré fringes, the focal length measured in the air of thelens immediately after removal from the lens mold is 10.87±0.23 mm(92.00 D±1.98 D) and after 96 hours apf exposure to ambient room lightis 10.74 mm±0.25 =mm (93.11 D±2.22 D). Thus, within the experimentaluncertainty of the measurement, it is shown that ambient light does notinduce any unwanted change in power. A comparison of the resultingRonchi patterns showed no change in spatial frequency or quality of theinterference pattern, confirming that exposure to room light does notaffect the power or quality of the inventive IOLs.

EXAMPLE 12

Effect of the Lock in Procedure of an Irradiated IOL

An inventive IOL whose power had been modulated by irradiation wastested to see if the lock-in procedure resulted in further modificationof lens power. An IOL fabricated from 60 wt % PDMS, 30 wt % RMC monomerE, 10 wt % RMC monomer F, and 0.75% DMPA relative to the two RMCmonomers was irradiated for two minutes with 0.75 mW/cm² of the 325 nmlaser line from a He:Cd laser and was exposed for eight minutes to amedium pressure Hg arc lamp. Comparisons of the Talbot images before andafter the lock in procedure showed that the lens power remainedunchanged. The sharp contrast of the interference fringes indicated thatthe optical quality of the inventive lens also remained unaffected.

To determine if the lock-procedure was complete, the IOL was refittedwith a 1 mm diameter photomask and exposed a second time to 0.75 mW/cm²of the 325 laser line for two minutes. As before, no observable changein fringe space or in optical quality of the lens was observed.

EXAMPLE 13

Monitoring for Potential IOL Changes from the Lock-in

A situation may arise wherein the implanted IOL does not requirepost-operative power modification. in such cases, the IOL must be lockedin so that its characteristic will not be subject to change. Todetermine if the lock-in procedure induces undesired changes in therefractive power of a previously unirradiated IOL, the inventive IOL(containing 60 wt % PDMS, 30 wt % RMC monomer E, 10 wt % RMC monomer F,and 0.75 wt % DMPA relative to the two RMC monomers) was subject tothree 2 minute irradiations over its entire area that was separated by a3 hour interval using 0.75 mW/cm² of the 325 laser line from a He:Cdlaser. Ronchigramns and moiré fringe patterns were taken prior to andafter each subsequent irradiation. The moiré fringe patterns taken ofthe inventive IOL in air immediately after removal from the lens moldand after the third 2 minute irradiation indicate a focal length of10.50 mm±0.39 mm (95.24 D±3.69 D) and 10.12 mm±0.39 mm (93.28 D±3.53D)respectively. These measurements indicate that photolocking a previouslyunexposed lens does not induce unwanted changes in power. In addition,no discernable change in fringe spacing or quality of the Ronchi fringeswas detected indicating that the refractive power had not changed due tothe lock-in.

What is claimed is:
 1. An optical element comprising: a first polymermatrix and a refraction modulating composition dispersed therein,wherein the refraction modulating composition is capable ofstimulus-induced polymerization, such that a stimulus causes a desiredchange of refraction, without subsequent removal of the refractionmodulating composition.
 2. The optical element as in claim 1 wherein therefraction modulating composition is capable of photo-inducedpolymerization.
 3. The optical element as in claim 1 wherein the opticalelement is a prism.
 4. The optical element as in claim 1 wherein theoptical element is a lens.
 5. A lens comprising: a first polymer matrixand a refraction modulating composition dispersed therein, wherein therefraction modulating composition is capable of photo-inducedpolymerization, such that light causes a desired change of refraction,without subsequent removal of the refraction modulating composition. 6.The lens as in claim 5 wherein the first polymer matrix is selected fromthe group consisting of poly-acrylate, poly-methacrylate, poly-vinyl,poly-siloxane, and poly-phosphazene.
 7. The lens as in claim 6 whereinthe first polymer matrix includes a poly-siloxane.
 8. The lens as inclaim 6 wherein the first polymer matrix includes a poly-acrylate. 9.The lens of claim 5 wherein the refraction modulating compositionincludes a component selected from the group consisting of an actylate,methacrylate, vinyl, siloxane and phosphazene.
 10. The lens as in claim5 wherein the refraction modulating composition comprises a monomer ofthe formula X—Y—X¹ and a photoinitiator wherein Y is

wherein: m and n are each independently an integer and R¹, R², R³, R⁴,R⁵, and R⁶ are each independently selected from the group consistinghydrogen, alkyl, aryl, and heteroaryl; and Z is a photopolymerizablegroup.
 11. The lens as in claim 10 wherein R¹, R², R³, R⁴, R⁵, and R⁶are each independently a C₁-C₁₀ alkyl or phenyl and Z is includes amoiety selected from the group consisting of acrylate, allyloxy,cinnamoyl, methacrylate, cinnamoyl, stibenyl, and vinyl.
 12. The lens asin claim 11 wherein R¹, R², and R³, R⁵, and R⁶ are selected from thegroup consisting of methyl, ethyl and propyl and R⁴ is phenyl.
 13. Thelens as in claim 11 wherein the monomer is (i)dimethylsiloxane-diphenylsiloxane copolymer endcapped with avinyldimethylsilane group, (ii) dimethylsiloxane-methylphenylsiloxanecopolymer endcapped with a methacryloxypropyldimethylsilane group, or(iii) dimethylsiloxane encapped with a methacryloxypropyldimethylsilanegroup and the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone. 14.An intraocular lens comprising: a polysiloxane matrix and a refractionmodulating composition dispersed therein, wherein the refractionmodulating composition is capable of photo-induced polymerization, suchthat light causes a desired change of refraction, without subsequentremoval of the refraction modulating composition.
 15. The intraocularlens as in claim 14 wherein the polysiloxane matrix is polydimethylsiloxane endcapped with diacetoxymethylsilane.
 16. The intraocular lensas in claim 14 wherein the refraction modulating composition comprises:dimethylsiloxane-diphenylsiloxane copolymer endcapped with avinyldimethylsilane group; dimethylsiloxane-methylphenylsiloxanecopolymer endcapped with a methacryloxypropyldimethylsilane group; ordimethylsiloxane encapped with a methacryloxypropyldimethylsilane group;and, 2,2-dimethoxy-2-phenylacetophenone.
 17. A method of implementing anoptical element having a refraction modulating composition dispersedtherein, comprising: (a) exposing at least a portion of the opticalelement to a stimulus whereby the stimulus induces the polymerization ofthe refraction modulating composition, such that the stimulus causes adesired change of refraction, without subsequent removal of therefraction modulating composition.
 18. The method as in claim 17 whereinthe optical element is a prism or a lens.
 19. The method as in claim 17wherein the exposed portion represents the entire optical element. 20.The method as in claim 17 further comprising: (b) waiting an interval oftime; and (c) re-exposing the portion of the optical element to thestimulus to induce the further polymerization of the refractionmodulating composition within said portion, such that the stimulusproduces a desired change of refraction, without subsequent removal ofthe refraction modulating composition.
 21. The method as in claim 20further comprising repeating steps (b) and (c).
 22. The method of claim20 or 21 further comprising exposing the entire optical element to thestimulus.
 23. A method of implementing an intraocular lens having arefraction modulating composition dispersed therein and implanted withinthe eye, comprising: (a) exposing at least a portion of the lens to alight source whereby the light source induces the polymerization of therefraction modulating composition, such that stimulus from the lightsource causes a desired change of refraction, without subsequent removalof the refraction modulating composition.
 24. The method as in claim 23wherein the exposed portion represents the entire intraocular lens. 25.The method as in claim 23 further comprising: (b) waiting an interval oftime; and (c) re-exposing the portion of the lens to the light source toinduce the further polymerization of the refraction modulatingcomposition within said portion, such that the light produces a desiredchange of refraction, without subsequent removal of the refractionmodulating composition.
 26. The method as in claim 25 further comprisingrepeating steps (b) and (c).
 27. The method of claim 25 or 26 furthercomprising exposing the entire lens to the light source.
 28. The methodas in claim 23 wherein the exposed portion is the optical zone of thelens.
 29. The method as in claim 23 wherein the exposed portion is theouter rim of the lens.
 30. The method as in claim 23 wherein the exposedportion is along a meridian of the lens.
 31. A method of implementing anintraocular lens having a refraction modulating composition dispersedtherein and implanted within the eye, comprising: (a) exposing a firstportion of the lens to a light source whereby the light source inducesthe polymerization of the refraction modulating composition, such thatthe stimulus from the light causes a desired change of refraction, and(b) exposing a second portion of the lens to the light Source, such thatstimulus from the light source causes a desired change of refraction,and (c) producing the desired change without subsequent removal of therefraction modulating composition.
 32. The method as in claim 31 furthercomprising exposing a third portion of the lens to light whereby thelight induces polymerization of the refraction modulating compositionsuch that the light causes a desired change of refraction, withoutsubsequent removal of the refraction modulating composition.
 33. Themethod as in claim 31 further comprising exposing the entire lens to thelight source.
 34. A lens comprising: a refraction modulating compositiondispersed in said lens wherein said refraction modulating composition iscapable of stimulus-induced polymerization and is freely diffusablewithin at least a portion of the lens, such that a stimulus causes adesired change of refraction, without subsequent removal of therefraction modulating composition.
 35. The lens of claim 34 furthercomprising a first polymer matrix.
 36. The lens of claim 35 wherein saidrefraction modulating composition is capable of forming a second polymermatrix.
 37. The lens of claim 35 wherein said first polymer matrix isselected from the group consisting of polyacrylate, polymethacrylate,polyvinyl, polysiloxane, and polyphosphazene.
 38. The lens of claim 35wherein the first polymer matrix includes a polysiloxane.
 39. The lensof claim 35 wherein the first polymer matrix includes a polyacrylate.40. The lens of claim 35 wherein said first polymer matrix is formedfrom polydimethylsiloxane endcapped with diacetoxymetylsilane.
 41. Thelens of claim 34 wherein the refraction modulating composition iscapable of photo-induced polymerization.
 42. The lens of claim 34wherein the lens is an intraocular lens.
 43. The lens of claim 34wherein said refraction modulating composition is biocompatible.
 44. Thelens of claim 34 further comprising a photoinitiator.
 45. The lens ofclaim 34 wherein said refraction modulating composition includes acomponent selected from the group consisting of an acrylate,methacrylate, vinyl, siloxane, and phosphazene.
 46. The lens of claim 34wherein the refraction modulating composition comprises a monomer of theformula X—Y—X¹ and a photo-initiator wherein Y is

respectively, wherein m and n are independently an integer and R¹, R²,R³, R⁴, R⁵, and R⁶ are each independently selected from the groupconsisting of hydrogen, alkyl, aryl and heteroaryl and Z is aphoto-polymerizable group.
 47. The lens of claim 46 wherein R¹, R², R³,R⁴, R⁵ and R⁶ are each independently a C₁-C₁₀ alkyl or phenyl and Zincludes a moiety selected from the group consisting of acrylate,methacrylate, allyloxy, cinnamoyl, stibenyl, and vinyl.
 48. The lens ofclaim 46 wherein R¹, R², R³, R⁵ and R⁶ are selected from the groupconsisting of methyl, ethyl and propyl and R⁴ is phenyl.
 49. The lens ofclaim 46 wherein the momnomer is (i) dimethylsiloxane-diphenylsiloxanecopolymer endcapped with a vinyldimethylsilane group, (ii)dimethylsiloxane-methylphenylsiloxane copolymer endcapped with amethacryloxypropyldimethylsilane group, or (iii) dimethylsiloxaneendcapped with a methacryloxypropyldimethylsilane group.
 50. The lens ofclaim 34 wherein said refraction modulating composition comprisesdimethylsiloxane-methylphenylsiloxane copolymer endcapped withmethacryloxypropyidimethylsilane.
 51. A lens comprising: a first polymermatrix; a refraction modulating composition dispersed in said firstpolymer matrix wherein said refraction modulating composition is capableof stimulus-induced polymerization and is freely diffusable within atleast a portion of the lens, such that a stimulus causes a desiredchange of refraction, without subsequent removal of the refractionmodulating composition.
 52. The lens of claim 51 wherein said refractionmodulating composition is capable of photo-induced polymerization. 53.The lens of claim 51 wherein said refraction modulating composition iscapable of forming a second polymer matrix.
 54. The lens of claim 51wherein the lens is an intraocular lens.
 55. The lens of claim 51wherein said refraction modulating composition is biocompatible.
 56. Thelens of claim 51 further comprising a photoinitiator.
 57. The lens ofclaim 51 wherein said refraction modulating composition includes acomponent selected from the group consisting of an acrylate,methacrylate, vinyl, siloxane, and phosphazene.
 58. The lens of claim 51wherein said first polymer matrix is selected from the group consistingof polyacrylate, polymethacrylate, polyvinyl, polysiloxane, andpolyphosphazene.
 59. The lens of claim 51 wherein the refractionmodulating composition comprises a monomer of the formula X—Y—X¹ and aphoto-initiator wherein Y is

respectively, wherein m and n are independently an integer and R¹, R²,R³, R⁴, R⁵, and R⁶ are each independently selected from the groupconsisting of hydrogen, alkyl, aryl and heteroaryl and Z is aphoto-polymerizable group.
 60. The lens of claim 59 wherein R¹, R², R³,R⁴, R⁵ and R⁶ are each independently a C₁-C₁₀ alkyl or phenyl and Zincludes a moiety selected from the group consisting of acrylate,methacrylate, allyloxy, cinnamoyl, stibenyl, and vinyl.
 61. The lens ofclaim 51 wherein the first polymer matrix includes a polysiloxane. 62.The lens of claim 51 wherein the first polymer matrix includes apolyacrylate.
 63. The lens of claim 51 wherein the polysiloxane matrixis polydimethylsiloxane endcapped with diacetoxymethylsilane.
 64. Thelens of claim 51 wherein the refraction modulating composition comprises(i) dimethylsiloxane-diphenylsiloxane copolymer endcapped with a vinyldimethylsilane group, (ii) dimethylsiloxane-methylphenylsiloxanecopolymer endcapped with a methacryloxypropyldimethylsilane group, or(iii) dimethylsiloxane endcapped with a methacryloxypropyldimethylsilanegroup.
 65. An intraocular lens comprising: a first polymer matrix; arefraction modulating composition dispersed in said first polymer matrixwherein said refraction modulating composition is capable ofstimulus-induced polymerization and is freely diffusable within at leasta portion of said first polymer matrix, such that a stimulus causes adesired change of refraction, without subsequent removal of therefraction modulating composition.
 66. The intraocular lens of claim 65wherein said refraction modulating composition is capable of forming asecond polymer matrix.
 67. The intraocular lens of claim 65 wherein saidrefraction modulating composition is capable of photo-inducedpolymerization.
 68. The intraocular lens of claim 65 wherein saidrefraction modulating composition is biocompatible.
 69. The intraocularlens of claim 65 further comprising a photoinitiator.
 70. Theintraocular lens of claim 65 wherein said refraction modulatingcomposition includes a component selected from the group consisting ofan acrylate, methacrylate, vinyl, siloxane, and phosphazene.
 71. Theintraocular lens of claim 65 wherein said first polymer matrix isselected from the group consisting of polyacrylate, polymethacrylate,polyvinyl, polysiloxane, and polyphosphazene.
 72. The intraocular lensof claim 65 wherein the refraction modulating composition comprises amonomer of the formula  X—Y—X¹ and a photo-initiator wherein Y is

respectively, wherein m and n are independently an integer and R¹, R²,R³, R⁴, R⁵, and R⁶ are each independently selected from the groupconsisting of hydrogen, alkyl, aryl and heteroaryl and Z is aphoto-polymerizable group.
 73. The intraocular lens of claim 65 whereinthe first polymer matrix includes a polysiloxane.
 74. The lens of claim72 wherein R¹, R², R³, R⁴, R⁵ and R⁶ are each independently a C₁-C₁₀alkyl or phenyl and Z includes a moiety selected from the groupconsisting of acrylate, methacrylate, allyloxy, cinnamoyl, stibenyl, andvinyl.
 75. The intraocular lens of claim 65 wherein the first polymermatrix includes a polyacrylate.
 76. The intraocular lens of claim 65wherein said first polymer matrix is formed from poly-dimethylsiloxaneendcapped with diacetoxymethylsilane.
 77. The intraocular lens of claim65 wherein said refraction modulating composition comprisesdimethylsiloxane-methylphenylsiloxane copolymer endcapped withmethacryloxypropyldimethylsilane.
 78. A method of adjusting therefraction of a lens having a refraction modulating compositiondispersed therein, comprising (a) exposing at least a portion of thelens to an external stimulus wherein the external stimulus induces thepolymerization of the refraction modulating composition in the portionof the lens exposed to the stimulus, such that the stimulus causes adesired change of refraction, without subsequent removal of therefraction modulating composition.
 79. The method of claim 78 furthercomprising (b) waiting an interval of time; and (c) exposing a portionof the lens to the stimulus to induce further polymerization of therefraction modulating composition, such that the stimulus causes adesired change of refraction, without subsequent removal of therefraction modulating composition.
 80. The method of claim 79 furthercomprising repeating the steps (b) and (c).
 81. The method of claim 79or 80 further comprising exposing the entire lens to the stimulus. 82.The method of claim 79 wherein said external stimulus is light.
 83. Themethod of claim 79 wherein said external stimulus is ultraviolet light.